Closure mechanisms and locks for windows are known in the art. For many years, windows have utilized various mechanisms to secure closure, primarily for safety, security, and energy efficiency. In particular, double hung window assemblies, which have an upper sash window and a lower sash window mounted within a common frame, have typically used sash locks, which draw the upper and lower sashes together to prevent sliding.
Such sash locks generally incorporate a housing mounted on one sash and a keeper mounted on the opposite sash. A lever or actuator arm handle is mounted atop the housing. The handle serves to move an internal mechanism between locked and unlocked positions. Specifically, the surface of the cam engages a tooth-like protrusion of the keeper in the locked position.
Several problems exist with current sash lock technology. First, the physical force exerted on the engaging surfaces creates an undue amount of stress on all parts of the lock. Failures often occur when the cam breaks at its point of intersect with the tooth-like protrusion or the handle, when the keeper breaks in the vicinity of the tooth-like protrusion, or when the handle breaks during operation.
Second, current lock construction demands exacting alignment of the finished product when installed. If this is not achieved, the security function of the window is compromised (i.e., the mechanism will not engage the keeper and thus lock the window). If only partial alignment is achieved, undue stress will be placed on window and lock components, leading to failure of the window and the lock. This scenario is increasingly likely as the window and surrounding construction ages.
Third, the surface engagement mechanism used by current sash locks can push the window sashes away from one another. Conversely, the mechanism can pull the sashes together with excessive force. The result in either case can be misalignment of the window sashes when the window is locked. This compromises the safety and energy efficiency functions of the window.
Thus, there is a need for improvement of current locking window technology that avoids these shortcomings, yet provides greater security and efficiency benefits.